Recently, the installation of security cameras is increasing due to crime prevention, monitoring, information gathering, or the like. Conventionally, captured images of a security camera are transmitted via a wired network. However, due to difficulties in wiring and an increase in installation cost, attempts have been made to transmit captured images via a wireless communication network such as Wi-Fi or Long-Term Evolution (LTE).
However, in the case of conventional Wi-Fi, which is a wireless transmission method based on single-input and single-output (SISO), data transmission is interrupted due to multi-pass fading according to delay (time delayed reflected wave) of a received signal caused by a surrounding environment such as an obstacle. When a data transmission rate is lowered due to various wireless communication environment variables, the degradation of a high-quality image occurs because a method of increasing data compression rate is used.
Further, although a high-output patch antenna is used for long distance transmission, the mounting cost is increased, and positions and directivity of transmission and reception antennas should be considered, and thus there is difficulty in installation. An antenna having a high gain such as a patch antenna is applied only to outdoor standards, and thus the antenna cannot be used in an indoor long-distance transmission.
Meanwhile, in the case of LTE, there is a restriction for service to be provided through a designated network service provider, the system construction cost for the related service is high, and the service user has to pay an LTE data fee. Therefore, LTE is a wireless image transmission method that is a heavy burden for both the operators and the consumers.